Этот бутон ещё не открылся, зато другая роза уже пахнет очень приятно.

Because Russian adjectives and pronouns must agree with the noun in gender, number, and case.

• бутон is masculine singular, so we use этот
• роза is feminine singular, so we use другая

So:

• этот бутон = this bud
• другая роза = another / a different rose

The same agreement rule applies throughout Russian.

They are both in the nominative case because they are the subjects of their clauses.

• Этот бутон ещё не открылся = This bud has not opened yet
• другая роза уже пахнет очень приятно = another rose already smells very pleasant

In both parts, the noun is doing the action or being described as in a state, so nominative is used.

Because открыться means to open in the sense of to open up / to become open, while открыть means to open something.

Compare:

• Я открыл дверь. = I opened the door.
• Дверь открылась. = The door opened.

So:

• открылся = opened / has opened
• the -ся shows that the subject itself underwent the change

With бутон, this makes perfect sense: a bud opens by itself, so Russian uses открыться.

In the past tense, Russian verbs agree with the subject in gender and number.

Since бутон is masculine singular, the past form is:

• открылся = masculine singular

Other possibilities would be:

• открылась for a feminine noun
• открылось for a neuter noun
• открылись for plural

So бутон открылся is masculine because бутон is masculine.

These two words create a useful contrast:

• ещё не = not yet
• уже = already

So the sentence contrasts two situations:

• Этот бутон ещё не открылся = This bud has not opened yet
• другая роза уже пахнет очень приятно = another rose already smells very pleasant

This helps show that one flower is behind in development, while the other is already at a later stage.

Зато is a contrast word. It often means something like:

• but on the other hand
• but at least
• however, in compensation
• whereas

It introduces a positive or balancing contrast.

In this sentence:

• Этот бутон ещё не открылся, зато другая роза уже пахнет очень приятно.

The idea is:

• This bud hasn’t opened yet, but on the other hand another rose already smells very nice.

So зато is not just plain but. It often suggests one thing is lacking, but there is some compensating positive point.

Because after пахнуть (to smell), Russian usually uses an adverb-like word to describe how something smells, not an adjective agreeing with the noun.

So:

• роза пахнет приятно = the rose smells pleasant / pleasantly

Here приятно means pleasantly or pleasant in an adverbial sense.

Compare:

• приятная роза = a pleasant rose
  This describes the rose itself with an adjective.
• роза пахнет приятно = the rose smells pleasant
  This describes the quality of the smell.

So приятно is the correct form here.

Because Russian uses the present tense to describe a current state or ongoing fact.

• пахнет = smells / is smelling

In English, smells is the natural translation:

• другая роза уже пахнет очень приятно = the other/another rose already smells very nice

This means that right now the rose is giving off a pleasant smell.

It can mean another rose or a different rose, depending on context.

• другой / другая / другое often means other, another, or different

In this sentence, другая роза most naturally means:

• another rose
• or a different rose

If the context has only two roses, English might translate it as the other rose. Russian often leaves that to context.

Russian usually does not use a present-tense form of to be in ordinary sentences.

So where English says:

• This is a bud
• The rose is beautiful

Russian normally says simply:

• Это бутон
• Роза красивая

In your sentence, there is no missing is because the main verbs are already there:

• не открылся = has not opened
• пахнет = smells

Russian does have forms of to be, but in the present tense they are usually omitted in this kind of sentence.

Yes. Russian word order is more flexible than English, although the original version sounds natural and well-balanced.

Original:

• Этот бутон ещё не открылся, зато другая роза уже пахнет очень приятно.

You might also hear variations like:

• Этот бутон не открылся ещё, зато другая роза уже пахнет очень приятно.
• Зато другая роза уже пахнет очень приятно, а этот бутон ещё не открылся.

Changing the order can shift the focus or emphasis, but the basic meaning stays similar.

The original order is good because it clearly contrasts:

1. this bud — not yet open
2. another rose — already fragrant

Because the sentence is about the result: the bud has not reached the state of being open yet.

• открыться = perfective, focusing on the completed change
• открываться = imperfective, focusing on the process or repeated action

So:

• бутон ещё не открылся = the bud has not opened yet
• бутон открывался would mean something more like the bud was opening / used to open, which does not fit this context

With ещё не, perfective is very common when talking about something that has not happened yet but is expected to happen.

No. Ещё can mean different things depending on context.

Common meanings include:

• still
• yet
• more
• another

In this sentence, with negation:

• ещё не = not yet

Examples:

• Я ещё дома. = I’m still at home.
• Я ещё не дома. = I’m not home yet.
• ещё один = one more / another one

So here you should understand ещё не открылся as has not opened yet, not is still not opening.